1. Field of the Invention
The present invention relates to a battery unit and a battery energy billing method.
2. Description of the Related Art
Some battery-powered apparatus use electrical energy stored in a stationary battery unit and another battery-powered apparatus use electrical energy stored in a replaceable battery unit, such as a cartridge battery. When the stationary battery unit is used, the quantity of electrical energy used by the apparatus can be easily known from the quantity of electrical energy necessary for charging the stationary battery unit and the charge on the used electrical energy can be determined by multiplying the quantity of electrical energy used for charging by the power rate.
Generally, the replaceable cartridge battery for supplying electrical energy to mobile broadcasting apparatus, electric motors and the like is replaced with a fully-charged replaceable cartridge battery before the same is exhausted to obviate troubles. Accordingly, it is difficult to establish a battery energy billing method for the replaceable cartridge battery, particularly, when the supplier and the user of the replaceable cartridge battery are different. The difficulty in establishing a battery energy billing method is an impediment to the popularization of the replaceable cartridge battery.
If battery charging charge is fixed regardless of the degree of discharge of replaceable cartridge batteries, the battery energy charge will be excessively high and electrical energy is costly and the user will be worried about balancing saving power charge and obviating troubles resulting from the exhaustion of the replaceable cartridge battery.